Some Pokmon have no retreat cost, while others (especially larger, more powerful Pokmon) may require multiple Energy cards to retreat
If your budget is limited and your goal is collecting or investing, I recommend booster boxes first, ETBs for extras
Honorable Mention - Order of Midnight Order of Midnight is one of two potential cards, you choose
Jumpstart boosters are made specifically for this format
5 Erika Grass Pokemon Will Be Thankful Effect: Heal 50 damage from 1 of your Grass Pokemon Energy: Grass Favored Pokemon: Vileplume, Victreebel & Tangela Erika is the Grass-type Pokemon Gym Leader of Celadon City, and her supporter card fits that to a tee with its ability to heal a massive 50 damage to a Grass Pokemon card
There is a possibility that there are scratches, befoul warping, and other age-related deterioration